In the hydrocarbon exploration and production industries, it is common for offshore production systems to have arrangements of subsea infrastructure that include fluid conduits which connect various subsea manifolds to subsea wellheads, and connect subsea components to surface facilities. An example of a simple hydrocarbon production system is shown in FIG. 1, generally depicted at 10. The offshore production system 10 comprises a surface installation 12, which in this case is a floating production storage and offloading vessel (FPSO) connected to a subsea wellhead 14, via a production flowline 16, a production manifold 18, and a flexible riser 20.
The system 10 also comprises an injection flow system, which in this example is formed from a subsea umbilical 22, comprising dynamic umbilical portion 22a and static umbilical portion 22b, and a chemical injection line 24. In this example, the static umbilical portion 22b is coupled to a chemical injection unit 23, to which the chemical injection line 24 is joined. In addition, in this embodiment, the dynamic umbilical portion 22a is joined to the static umbilical portion 22b via umbilical termination 21. In alternative arrangements, the umbilical termination unit 21 may be omitted, and the dynamic and static portions of the umbilical 22 may be directly joined.
During production operations, the umbilical 22 may be used to inject chemicals into the wellbore via the wellhead, for example to stimulate production. This typically involves pumping chemicals via a pump on the surface installation 12 through one or more of several fluid bearing cores contained in the umbilical 22. The umbilical may also comprise hydraulic control lines used to control hydraulically actuated devices or subsystems such as a valves or components of manifolds, which form a part of the subsea infrastructure.
From time to time it becomes necessary to clean or flush out one or more cores of the umbilical 22 to prevent a risk of blockage or damage. For example, flushing may be required if contamination or degradation of the chemicals contained within a core is detected, or it may be necessary to flush one or more cores of the umbilical prior to injection of a different chemical.
It is an aim of the invention to provide an apparatus for and a method of flushing a subsea fluid conduit, such as an umbilical flow line or a hydraulic control line. It is a further aim of the invention to provide an apparatus for and method of flushing subsea fluid conduits, such as an umbilical flow line or a hydraulic control line, which is economical and convenient to deploy and operate.
Other aims and objections of the invention will become apparent from reading the following description.